The invention relates to the treatment of light sensitive materials in general, and more particularly to improvements in the treatment of exposed flexible light sensitive sheet-like materials which are ready to be introduced into a developing machine. Still more particularly, the invention relates to improvements in methods of manipulating sheets of flexible light sensitive material which form one or more stacks in a dark box, e.g., in a magazine, cassette or an analogous receptacle or container for temporary storage of exposed sheets of light sensitive material.
X-ray equipment is utilized in numerous fields, for example, in medicine as well as in various industries, particularly for nondestructive testing of substances, tissues, materials and/or products. Equipment which relies on X-rays employs sheets which carry coatings of radiation-sensitive material. When the exposure of a sheet to a required amount of radiation is completed, the resulting latent image must be developed in a suitable developing machine. As a rule, or in many instances, the exposed but undeveloped sheets are introduced into a dark box while the dark box is confined in a darkroom, and the dark box is closed and sealed upon introduction of a desired number of exposed sheets or when the dark box is filled to capacity. The thus closed and sealed dark box is ready to be transported to a developing machine. A dark box which is ready to be emptied is coupled to a so-called feeder which withdraws discrete sheets, one after the other, and introduces the withdrawn sheets into a developing machine.
Sheets which are coated with radiation sensitive material are likely to exhibit, at least at times, a more or less pronounced tendency to adhere to each other. This creates problems when a feeder is called upon to withdraw single sheets, i.e., to withdraw successive uppermost or topmost sheets of a pile or stack of superimposed sheets. The situation is often aggravated due to the fact that the sheets are stacked in a dark box. Attempts to overcome the just outlined problem, i.e., to more reliably segregate successive uppermost sheets of a stack from the sheets immediately below them, include the utilization of suction cups which are caused to slightly flex portions of the uppermost sheets so that the tendency of neighboring sheets to adhere to each other is reduced or eliminated and the uppermost sheet can be readily extracted from the dark box. In most instances, such flexing of portions of uppermost sheets of a stack of radiation-sensitive sheets suffices to ensure that the feeder can admit into a developing machine discrete radiation sensitive sheets which carry latent images and are ready to be treated in a conventional manner, e.g., by causing them to pass through a series of baths prior to entering a drying chamber. In order to further enhance the likelihood of separation of each uppermost sheet from the sheet or sheets immediately therebelow, certain presently known feeders are designed in such a way that the suction cup or suction cups maintain the attracted portion of the uppermost flexible sheet in flexed condition for a certain interval of time which should suffice to ensure separation of the next-to-the-uppermost sheet from the flexed portion of the uppermost sheet. The aforementioned interval is variable to take into consideration the differences between various sheets and/or various formats of sheets. Such versatility of the feeder further enhances the likelihood of reliable separation of successive uppermost sheets of a stack of sheets from the immediately following sheets.
In accordance with a further proposal, apparatus which are used to transfer flexible sheets of exposed radiation sensitive material from a magazine or cassette into a developing machine are provided with means for monitoring successive extracted uppermost sheets in order to ascertain whether or not each extracted sheet has been extracted alone. If the monitoring system detects simultaneous extraction of two or more coherent sheets, such coherent sheets are returned into the magazine or cassette and the extracting or withdrawing procedure is repeated.